Biomedical subjects

Issa Loutfi

Publications and source records attributed to Issa Loutfi.

5 recordsLinked to original sources

PubMed2003

Salivary gland scintigraphy: the use of semiquantitative analysis for uptake and clearance.

OBJECTIVE: Quantitative analysis of (99m)Tc-pertechnetate salivary gland scintigraphy has been used in the evaluation of salivary gland function, but so far no one method can be considered optimal for this task. In this study, a semiquantitative method providing 2 functional parameters for objective assessment of salivary gland function by scintillation camera imaging was tested. METHODS: Twenty-one patients referred for (99m)Tc-pertechnetate thyroid scanning were studied. Two patients with salivary complaints were also included. Dynamic imaging of the anterior head using a scintillation camera was started after a bolus intravenous injection of 185 MBq (5 mCi) (99m)Tc-pertechnetate at 1 frame per 30 s for 30 min. At 15 min after injection, diluted lemon juice was administered orally. Analysis of the dynamic study included time-activity curves of 4 salivary glands (right and left parotid and right and left submandibular). Two parameters of function were defined: uptake rate, taken as the value of the initial slope of the time-activity curve, and washout fraction, which was the relative mobilizable radioactivity from each salivary gland after ingestion of the sialogogue. A parametric image of the washout fraction was also generated. RESULTS: The images showed gradual uptake in the parotid and submandibular glands. Washout was noted immediately after ingestion of the lemon juice. The pattern of the time-activity curve in all glands showed an early fast-rising part followed by a slow-rising component to nearly a plateau within 6-10 min after injection. The mean value of the uptake rate parameter was 0.10 +/- 0.09 cps/s. There was no significant difference between the parotid and submandibular glands or the right and left sides. Uptake in the parotid gland was 1.5-2 times that in the submandibular gland. The washout fraction was 1.40 +/- 1.60 for the parotid glands and 0.77 +/- 0.41 for the submandibular glands (P = 0.005). CONCLUSION: The quantitative analysis method including the uptake rate and the washout fraction parameters would enable objective assessment of salivary function and provide a reproducible means for follow-up of functional impairment in certain diseases.

Adolescent↗

PubMed2003

Nonosseous abnormalities on bone scans.

Although bone scanning is a test primarily concerned with skeletal abnormalities, important nonosseous findings are occasionally present on the images. To gauge the significance of such nonosseous uptake and, in particular, to determine whether these findings contain useful diagnostic information, the technical and medical staff in nuclear medicine must recognize the various patterns of nonbony uptake and understand their causes. The objectives of this article are to demonstrate the appearances of nonosseous uptake on bone scans, to categorize the forms of soft-tissue uptake, to emphasize technical artifacts leading to soft-tissue uptake, and to highlight the clinical significance of pathologic soft-tissue uptake.

Artifacts↗

PubMed2001

A mathematical model of optimized radioiodine-131 therapy of Graves' hyperthyroidism.

BACKGROUND: The current status of radioiodine-131 (RaI) dosimetry for Graves' hyperthyroidism is not clear. Recurrent hyperthyroidism and iatrogenic hypothyroidism are two problems which interact such that trying to solve one leads to exacerbation of the other. Optimized RaI therapy has therefore begun to be defined just in terms of early hypothyroidism (ablative therapy) as physicians have given up on reducing hypothyroidism. METHODS: Optimized therapy is evaluated both in terms of the greatest separation of cure rate from hypothyroidism rate (non-ablative therapy) or in terms of early hypothyroidism (ablative therapy) by mathematical modeling of outcome after radioiodine and critically discussing the three common methods of RaI dosing for Graves' disease. RESULTS: Cure follows a logarithmic relationship to activity administered or absorbed dose, while hypothyroidism follows a linear relationship. The effect of including or omitting factors in the calculation of the administered I-131 activity such as the measured thyroid uptake and effective half-life of RaI or giving extra compensation for gland size is discussed. CONCLUSIONS: Very little benefit can be gained by employing complicated methods of RaI dose selection for non-ablative therapy since the standard activity model shows the best potential for cure and prolonged euthyroidism. For ablative therapy, a standard MBq/g dosing provides the best outcome in terms of cure and early hypothyroidism.

Journal Article↗

PubMedDate not supplied

Minimizing radiation exposure from patients treated with iodine-131 for hyperthyroidism using a lead collar: a simple and effective approach.

OBJECTIVE: To construct a lead collar useful for shielding the electromagnetic radiation from the thyroid of patients treated with radioiodine (131)I for hyperthyroidism, thereby reducing the radiation emitted from these patients. MATERIALS AND METHODS: A specially designed cervical lead collar was used to shield radiation exposure from 'hot thyroids' of 20 patients treated with iodine-131 for hyperthyroidism. The collar was made of lead strips stacked together around a plastic neck support fastened around the patient's neck. Measurements of the radiation exposure rate were obtained at increasing distances from the patients (50, 100, 200 cm), with and without the lead collar, at various times after (131)I treatment. RESULTS: Radiation exposure measurements over 3 weeks showed relatively high exposure rates in the first week after treatment. The radiation exposure from the patients wearing the lead collar was half that found in the same patients not wearing the collar. CONCLUSION: The use of the lead collar significantly reduced the radiation exposure of patients' surroundings. It was particularly useful in patients who could not abide strictly to the standard restrictive protocols after treatment with (131)I.

Adolescent↗

PubMedDate not supplied

Post-test probability for pulmonary embolism after ventilation-perfusion scan assessed by nuclear medicine physicians.

OBJECTIVE: The objective of this prospective study was to compare assessments of pre- and post-ventilation-perfusion (V/Q) scan probabilities for pulmonary embolism (PE) by the nuclear medicine physician and the referring physician. MATERIALS AND METHODS: Seventy-nine patients (41 females, 38 males, mean age 49 years) referred for V/Q scans over a period of 6 months and suspected of PE were included in the study. The pre-test likelihood was determined independently by a consultant nuclear physician and a referring physician prior to the V/Q scan. The scan was performed according to a standard protocol using 8 view technetium-99m diethylenetriamine pentaacetic acid aerosol ventilation study followed by a technetium-99m macroaggregated albumin perfusion study. The scan was interpreted according to prospective investigation of pulmonary embolism diagnosis criteria. The post-scan probability was calculated. The probability of PE was quoted as low, intermediate and high. Agreement or disagreement in assessing the pre- and post-scan probability was classified according to the degree of difference (no difference: 0; minor difference: 1, and major difference: 2 grades). RESULTS: The agreement between the nuclear medicine and referring physicians on clinical probability of PE was moderate (63%) before the scan and good (90%) after the scan. The disagreement in assessing the clinical probability between the referring physician and the nuclear medicine physician was predominantly minor. Only 5 and 1% of the disagreement was major in pre-scan and post-scan probabilities, respectively. CONCLUSION: The data show that nuclear medicine physicians can use the assessment of pre-scan clinical likelihood to determine the post-scan probability of PE.

Adult↗